In recent years, interest in the field of micro-optics has continued to increase. For instance, miniature lenses, micro-lenses, and micro-lens arrays are in demand for applications involving optical computing, optical information processing, and communications. In one specific example, micro-lenses and micro-lens arrays are used in various apparatuses for coupling light from a laser to an optical fiber and coupling light from an optical fiber to a photo-detector. In another example, a micro-reflector or a micro-mirror may be used to direct the light or construct external cavities. Several embodiments of an apparatus where a parabolic reflector is used to promote single transverse mode operation from high-power, multi-mode broad area diode lasers are shown in U.S. Pat. No. 6,002,703 to Hwu et al. Several embodiments of an apparatus where a parabolic mirror is used to collimate and direct the light from a high-power, multi-mode broad area diode laser are shown in U.S. Pat. Nos. 5,995,289; 6,219,187 B1; and 6,259,713 B1. Because of the increased demand for micro-lenses, micro-lens arrays, micro-reflectors, and micro-mirrors in such applications, considerable effort has been made in developing methods for making micro-optic elements.
One existing method for making micro-lenses and micro-lens arrays comprises the steps of forming an array of photo-resist elements on a substrate, melting the elements to a curved shape, and thereafter solidifying the elements. The photo-resist elements and the substrate are then subjected to an etching process involving a reactive gas. This process is referred to in the art as reactive ion etching (RIE). The photo-resist elements cause differential etching in the substrate such that the dome shapes of the original photo-resist elements are replicated in the substrate. Unfortunately, prior art methods produce many optical elements having deviations that cause unwanted light dispersions. In addition, known methods of producing micro-lenses and micro-lens arrays cannot effectively produce a lens with a specific profile, such as an elliptical or parabolic profile.